The use of discrete test slides of various designs in automated instruments for the chemical analysis of fluid samples, such as human blood serum, is well known. For example, such a slide is disclosed in U.S. Pat. No. 4,151,931 and the patents and applications related thereto. However, it is believed that such slide systems have drawbacks which may interfere with their efficient use in chemical analyzers.
Such known slide systems generally require that the slides be organized into stacks which are disposed in a receiving container or cartridge which is adapted to be inserted into the analyzer. The analyzer mechanism is designed to sequentially remove the slides from the stack in the cartridge and transport them through the instrument where the fluid to be tested and various reagents and the like are deposited upon a reaction area located on the slide. The reaction area of the slide may have deposited thereon, as packaged in the cartridge, a dry reagent which is appropriate for conducting a particular test in the instrument, such as the detection of digoxin concentrations in blood serum. Other cartridges would house slide stacks suitable for conducting different blood chemistry tests.
In order to keep the remaining stack of test slides organized within the cartridge when it is removed from the analyzer for overnight storage, or whenever a test requiring a different reagent than that contained on the slides in the cartridge is to be conducted with the instrument, a relatively complicated mechanical slide stack organizing system within the cartridge is required. Hence, the expense of such cartridges, which are generally not reuseable, and of their internal slide organizing mechanisms contributes significantly to the per test cost of utilizing the analyzer.
Another drawback presented by slide cartridge systems is that they may indirectly interfere with the continuous automated operation of the analyzer. The reason for this is that when more tests requiring a particular reagent are to be run with the analyzer than slides remain in the cartridge, the operation of the analyzer must be interrupted to permit a new cartridge to be inserted. This is primarily due to the fact that additional slides cannot be inserted into the cartridge. The only alternate solution to this problem is to keep count of the slides remaining in the cartridge and to use a new, full slide cartridge when the number of tests to be conducted exceeds this remaining supply of slides. However, such a procedure becomes cumbersome when the number of different tests which the instrument is capable of conducting requires that a large variety of reagent slides and accompanying cartridges be maintained.